Geant4 simulations of the Columbus/ISS radiation environment

1. D E S I R EDose Estimation by Simulation of the ISS Radiation Environmenthttp://www.particle.kth.se/desire/ Geant4 simulations ofthe Columbus/ISS radiation environment T. Ersmark1, P. Carlson1, E. Daly2, C. Fuglesang3, I. Gudowska4, B. Lund-Jensen1,R. Nartallo2, P. Nieminen2, M. Pearce1, G. Santin2, N. Sobolevsky5 1Royal Institute of Technology (KTH) (Stockholm) 2ESA-ESTEC (Noordwijk) 3EAC/JSC (Cologne/Houston) 4Karolinska Institutet (Stockholm) 5Institute for Nuclear Research (Moscow)

2. Outline • The DESIRE project • Geant4 physics validation studies • Columbus and ISS geometries • Radiation environment models • Simulation results • Conclusions and future SPENVIS and Geant4 Workshop, Leuven, 051006, Tore Ersmark (KTH)

3. The DESIRE project • ”Dose Estimation by Simulation of the ISS Radiation Environment” • Aimed at accurate calculations of the radiation flux and doses to astronauts inside the European ISS laboratory Columbus. • Utilizes Geant4 for radiation transport. • Funded by ESA (15613/NL/LvH) and SNSB. • Validation and comparisons of Geant4 physics models to… • Experiments • NASA BRYN-/HZETRN programs • SHIELD-HIT Monte Carlo program • Implementation of Columbus and ISS geometries in Geant4. • Evaluation of incident radiation environment models. • Full simulations of particle fluxes and doses inside Columbus. SPENVIS and Geant4 Workshop, Leuven, 051006, Tore Ersmark (KTH)

4. Geant4 physics validation studies • Incident protons with energies 10-1000 MeV. • Neutron production • Energy deposition • Proton penetration • Water, Beryllium, Carbon,Aluminum, Iron, Uranium • Comparisons to Los Alamosexperimental data (Meier,Nucl. Sci. Eng. 102 and 104),SHIELD-HIT, BRYNTRN. • Published in IEEE Trans. Nucl. Sci. 51,1378 (2004).Summary: Energy deposition/proton penetration ok. Secondary neutron production ok after release of cascade models (since 2003). 113 MeV p on 4 cm Al 256 MeV p on 12 cm Al SPENVIS and Geant4 Workshop, Leuven, 051006, Tore Ersmark (KTH)

5. Columbus and ISSgeometries • “Columbus1” • Simple cylinder-like geometry • 10 volumes; MDPS1/2/3 + hull • 4200 kg • “Columbus3” • Detailed geometry • 800 volumes • 16750 kg • ISS • 350-400 volumes • 352 tons (369 tons) ...so 4 combinations SPENVIS and Geant4 Workshop, Leuven, 051006, Tore Ersmark (KTH)

6. The ISS Geant4 geometry JSC/SEMDA spec. Hull ... Interior ... Cabin ... Geant4 ... (CAM) SPENVIS and Geant4 Workshop, Leuven, 051006, Tore Ersmark (KTH)

7. The “Columbus3” Geant4 geometry SPENVIS and Geant4 Workshop, Leuven, 051006, Tore Ersmark (KTH)

8. Radiation environment models • Studied incident radiation fields • Trapped protons (isotropic and anisotropic) • GCR protons • SPE protons • (Cosmic ray albedo neutrons) • (Trapped electrons) • Other radiation fields • GCR ions • Solar ions • 51.6  330, 380, 430 km orbit • Web interfaces to models • SPENVIS (”SPV”) (http://www.spenvis.oma.be/spenvis/) • CREME96 (”C96”) (https://creme96.nrl.navy.mil) • SIREST (”SRS”) (http://sirest.larc.nasa.gov) SPENVIS and Geant4 Workshop, Leuven, 051006, Tore Ersmark (KTH)

9. Incident spectra • Incident particle spectra at 380 km and solar min • Belt protons • GCR protons • SPE protons • CR albedo neutrons SPENVIS and Geant4 Workshop, Leuven, 051006, Tore Ersmark (KTH)

10. Belt proton altitude dependence and anisotropy • Incident proton spectra at 330 km, 380 km, 430 km • Solar minimum/maximum • Anisotropy; spectra for protons coming from port and startboard-backward (at solar-minimum and 380 km) SPENVIS and Geant4 Workshop, Leuven, 051006, Tore Ersmark (KTH)

11. Simulation results • Spectra of particles enteringColumbus • Doses at 10 mm depthin ICRU sphere • Statistics... • 380 km andsolar minimumunless noted SPENVIS and Geant4 Workshop, Leuven, 051006, Tore Ersmark (KTH)

12. Belt protons Incident belt (AP8-MIN) protons at 380 km. Penetrating protons and neutrons. Belt proton doses at three altitudes for different geometry configurations. SPENVIS and Geant4 Workshop, Leuven, 051006, Tore Ersmark (KTH)

13. On-going study ofbelt proton anisotropy • Spectra for protons coming from • port • startboard-backward • SPENVIS AP8 • Anisotropy model ”UP” (Badhwar/Konradi) SPENVIS and Geant4 Workshop, Leuven, 051006, Tore Ersmark (KTH)

14. Cosmic ray protons Penetrating primary/secondary protons and secondary neutrons due to incident cosmic ray protons (CREME96-min, 380 km) SPENVIS and Geant4 Workshop, Leuven, 051006, Tore Ersmark (KTH)

15. Cosmic ray protons; Col3withISS Spectra of various particle species entering Columbus in the ”Col3withISS” geometry SPENVIS and Geant4 Workshop, Leuven, 051006, Tore Ersmark (KTH)

16. Cosmic ray proton doses Dose rates in ICRU sphere due to incident cosmic ray protons;itemized by geometry model and particle type at surface of sphere SPENVIS and Geant4 Workshop, Leuven, 051006, Tore Ersmark (KTH)

17. SPE protons & albedo neutrons SPE particle spectra and resulting doses Albedo neutron spectra and secondary protons SPENVIS and Geant4 Workshop, Leuven, 051006, Tore Ersmark (KTH)

18. Modell comparisons; Col3withISS • Belt protons: 135 vs. 520 Gy/d (!) • CR protons: 60 vs. 115 Gy/d • Albedo neutrons unimportant (several previous studies) SPENVIS and Geant4 Workshop, Leuven, 051006, Tore Ersmark (KTH)

19. Conclusions and future • A detailed model of Columbus and ISS (14A) has been implemented as Geant4 geometries. • Dose rates has been calculated for standard incident radiation field models • Belt protons (AP8-MIN): 135 Gy/d • Cosmic ray protons (CREME96, min): 60Gy/d • Cosmic ray albedo neutrons (SIREST): 0.5Gy/d • Study of the influence of belt proton anisotropy in progress. GCR- and solar ions will be studied the next few months. SPENVIS and Geant4 Workshop, Leuven, 051006, Tore Ersmark (KTH)